Yeah, her title as 'Calamity From the Sky' makes it clear Jenova is some form of extraterrestrial. Whether the Cetra are explicitly stated to travel from planet to planet I can't remember - but it seems to be the case, based on the description of their cultural life-cycle of exploring and 'unlocking' the planet. Their role, mythologically, is clearly to seed the planet with life and help cultivate the lifestream, but I don't recall if they're supposed to be planetary nomads or just nomads across Gaea. Obviously either way their journey ended after their run-in with Jenova.

EDIT: Just went over the lines again. While Sephiroth talks about them 'settling the planet and moving on', Aerith clarifies that the Cetra were in fact born from the Planet. So yeah, they're purely terrestrial nomads.

Yeah, the Cetra were nomads. Due to bad localization and confusing Japanese it was stated that they travel planets instead of the land. You should ditch the original localization entirely when discussing plot, because a lot of it is just plain wrong.

Fun fact... I have a cousin named Petra - and I decided on my first playthrough (I had never played RPG before) to name Aerith after her. So... you can imagine the "fun" I had. More confusing than ever. Petra was a Cetra.

As it looks now, a person has created the Black materia and cast meteor.

The Black Materia is Jenova's spaceship. It's also materia from Meteor. It's also what caused the northern crater. I can't remember where but Bugenhagen says that the northern crater will be nothing compared to what happens when Meteor comes.

I think Meteor's name as the "Ultimate destructive magic" is very telling. As Bugenhagen explains, when a planet loses all of its lifestream, it dies and falls apart and loses its orbit. I think Meteor injures the planet with the Black Materia, and then comes in and takes all the mako at the wound for itself. Especially because in the end video, it isn't just crashing into the planet, its slowly coming down.

He/she probably created also a way to absorb the lifestream to get more power (the virus) and became Jenova.

I agree in a way, except that the original Jenova did this on another planet, and became an organism that could manipulate its own lifestream, and is the only surviving member of the planet Meteor, where they store vast amounts of energy. Celestial bodies need a lifestream, and when you hit it with the rocket, those peices still stay "attached" to it.

If its a virus though, is it the virus or the person is a weird question. Does Jenova even have its own personality to begin with? Would that explain why you never interact with her? Do they all eventually go insane for not participating in the lifestream cycle and she needs fresh ones?

Congratulations! You just managed to add even less to the conversation then the person you regard as mentally retarded. Have a nice day.

(Ifalna)2000 years ago, our ancestors, the Cetra, heard the cries of the Planet.The first ones to discover the Planet’s wound were the Cetra at the Knowlespole.The Cetra then began a Planet-reading.It said something fell from the sky making a large wound.Thousands of Cetra pulled together, trying to heal the Planet…But, due to the severity of the wound, it was only able to heal itself over many years.The Planet tried to persuade the Cetra to leave the Knowlespole, but…When the Cetra…were preparing to part with the land they loved…That’s when the one who injured the Planet… or the ‘crisis from the sky’, as we call it, came.It first approached as a friend, deceived them, and finally, gave them the virus.The Cetra were attacked by the virus and went mad... and transformed into monsters(Sephiroth much?).Then, as it had in the Knowlespole.It approached the other Cetra clans... and infected them with... the virus.